1. Field of the Invention
The present invention relates to a laminated ink-jet recording head that includes an actuator unit, which is formed of ceramics, and a flow path substrate, which is formed of metal, that are connected to each other.
2. Related Art
In Japanese Unexamined Patent Publication No. Hei 6-040035, an ink-jet recording head is disclosed in which a piezoelectric vibration plate is bonded to an area of an elastic plate to form a pressure generation chamber, and in which to generate ink drops, the volume of the pressure generation chamber is varied by the flexing displacement of the piezoelectric vibration plate. This recording head is characterized in that it is able to generate ink drops stably because of the wide area of the pressure generation chamber that is variable.
In a recording head of this type, normally, an actuator unit, which is formed of ceramics and which includes a pressure generation chamber, a vibration plate and a piezoelectric vibration plate, is fixed by a bonding layer to a single flow path forming unit, which is made of a metal plate and which is so formed as to correspond to a plurality of nozzle openings which are formed in lines.
For such bonding, an adhesive, for example, can be used. However, when an adhesive is used, some accompanying problems arise. For example, the adhesive is not only difficult to apply, but it also may flow into and seal the nozzle openings and a lot of time is required for the adhesive to harden.
On the other hand, to solve these problems, and in particular, to simplify the application operation and to shorten the hardening time, a thermally fusible film is also used for such bonding. In this case as well, however, when pressure is applied to the thermally fusible film during the bonding operation, the thermally fusible film can be compressed and flattened to an unnecessary extent so that bonding layer thicknesses vary, or the film can flow into communication holes and close them. Further, there is a possibility that the thermally fusible film will now be sufficiently compressed and that a part of the film will be unevenly shaped. Then, when the unevenly shaped film is interposed between the substrates to bond them together, a sufficient bonding strength cannot be obtained.
The present invention is intended to eliminate the above problems that arise with a conventional ink-jet recording head. Accordingly, it is an object of the invention to provide a laminated ink-jet recording head which uses as bonding means a thermally fusible film that does not close communication holes and can provide a sufficient bonding strength.
It is also an object of the present invention to provide an ink-jet recording head that allows the components of the head to be securely bonded together by employing thermally fusible films.
In achieving the above object, according to the present invention, there is provided an ink-jet recording head, comprising:
an actuator unit, which includes a plurality of first cover members and spaces respectively formed of ceramics, the first cover members and the spacers being integrally bonded to each other, with each of the first cover members having mounted on one surface a plurality of piezoelectric vibration plates so as to provide a vibration means, and with one surface of each of the spacers being sealed by the first cover member so as to form a plurality of pressure generation chambers; and
a flow path unit, which is bonded to the actuator unit, that includes: an ink supply port forming substrate formed of metal, to which the actuator unit can be fixed and which also includes a plurality of communication holes and a plurality of ink supply ports, formed respectively on the two side ends of the pressure generation chambers; a common ink chamber forming substrate, which is formed of metal, that includes a plurality of ink chambers, which respectively communicate with the pressure generation chambers through the ink supply ports, and a plurality of communication holes, which communicate with the pressure generation chambers; and a nozzle plate, which is formed of metal, that seals the other surface of the common ink chamber forming substrate and that includes a plurality of nozzle openings that are connected with the pressure generation chambers by the respective communication holes, wherein the ink supply port forming substrate, the common ink chamber forming substrate and the nozzle plate being bonded to each other by an adhesive so as to provide the flow path unit, and wherein the ink supply port forming substrate, the common ink chamber forming substrate and the nozzle plate are bonded together by inserting between them thermally fusible films, in each of which, film through holes are formed at two or more positions, and by also supplying, by means of the film through holes, an adhesive mixed with a gap material for adjusting the thickness of the thermally fusible films when they are fused, to provide the flow path unit, and then the flow path unit and the actuator unit are bonded together by inserting between them a thermally fusible film, in which through holes are formed at two or more positions, and by an adhesive that is mixed with a gap material, with which the film through holes are filled, for adjusting the thickness of the thermally fusible film when it is fused.
According to the invention, an extruded quantity of thermally fusible film can be accepted by the through holes formed at important locations in the thermally fusible film, and the gap material with which the through holes in the film are filled prevents the unnecessary spreading of the thermally fusible film.